Process and apparatus for manufacturing flexible tubes



Sept. 27, 1932. DREYER 1,379,663

PROCESS AND APPARATUS FOR MANUFACTURING FLEXIBLE TUBES Filed Jan. 10. 1950 Patented Sept. 27, 1932 ALBERT DREYER, Oil LUCERNE, SWITZERLATTD PROCESS AND APPARATUS FOR MANUFACTURING FLEXIBLE TUBES Application filed January 10, 1930, Serial No.

The invention relates to a process and an ap aratus for manufacturing hignly elastic flexible tubes, by shaping deep corrugations in thin-willed plain tubes of copper, tombac,

: brass, iron, and the like.

Such flexible tubes (which are finding pro gressively increasing application for the most divergent purposes, such as temperature regulators, valves, pressure regulators, electric contact releases, fire alarms, mixing valves, compensators, brass instruments, diaphragms, stuffing boxes, valveless pumps, and so forth) have hitherto been manufactured by rolling corrugations in the plain tubes, the material having, in most instances, to be frequently annealed between the various working stages, because it increases in hardiness, but decreases in ductility, through the cold-rolling.

' In some processes, the corrugations are. forced outwards exclusively, in others solely inwards. In the. outward process, the material is subjected to considerable elongation stresses, whilst the corrugations obtained by this process are considerably smaller, as re-- gards depth, than in the inward-process,

in which the material has to be displaced, to a certain extent, in rolling the corrugation troughs inwardly, a circumstance favorable to increasing the height of the crests. Hence, the second mentioned process affords the possibility of giving deeper corrugationscombined with less stressing of the material (see the U. S. Patent No. 1614563, of Edgar J.

r Leach and \V alter C. Lagerman, dated 18th January, 1927).

Experience has now shown that the greatest stressing in such flexible tubes occurs in the troughs of the corrugations, and that fatigue and fracture are practically confined to said troughs, unless the material at the crests has been so greatly elongated and stressed, by excessi we outward rolling of the corrugations, that the walls there have become much thinner and the material far harder so that, de-

419848, and in Germanyianuar y 18, 1929.

spite lesser stressing, cracks occur prematurely there, in use. Generally speaking, however, in the case of properly manufactured flexible tubes, fracture always occurs in the troughs of the corrugations.

The object of the present invention is to' remedy this inconvenience by insuringthat the material will be stressed in a far more uniform manner than inexisting processes; When the corrugations are exclusively rolled towards the interior, the finished corrugation of the flexible tube also displays a substantially greater external diameter than the thin-walled tube employed. This permits the deduct-ion thatconsiderable quantities of material must be displaced in rolling-in the troughs of the corrugations. It also admits of the conclusion that the material would be most uniformly stressed if the corrugations were formed, partly by forcing them 'out- Wards and partly by forcing them inwards, to an approximately equalextent. This new discovery forms the basis of this invention, the essential feature of which consists in pressing the designed corrugations, partly 7o outwards and partly inwards, in an approximately equal degree. The principal result thus obtained is that substantially still deeper corrugations are obtained, combined with uniform wall thickness and maximum protection of the material. Owing to the circum stance that, with this method of treatment, the material is subjected to considerably less stressing, the annealing between the several working stages can be dispensed with. More? over, in consequence of the substantially deeper corrugations obtainable, the elasticity, and therefore the working life, of the flexible articles is considerably increased.

According to the invention, the formation of the crests of the corrugations is efiected by means of a ram of yielding material, preferably rubber, or by a pressure fluid ram. The advantage of such a tool consists in that the stressing of the material is very uniform, in

contrast to rolling the material with the usual pressure rolls, in which case the material is stressed in a far. more irregular and forcible manner. Such rolls are generally of comparatively small diameter, in order to enable them to be easily withdrawn from the tube after impressing the trough of the corrugation; strictly speaking, they are only able to treat the work at a single point, and thus modify the material in a more or less stratified manher, so that the material cannot be transformed so uniformlyas when the entire periphery of'the corrugation is shaped simultaneously in the manner possibleby means of a rubber ram. Since a roll acts at only one point, that is, a small fraction of the periphery of the tube, the material cannot flow, but, on the contrary, is exclusively stressed by elongation, because the remainder of the periphery, which is not simultaneously acted upon by the roll, prevents sectional reduction of the material. \Vith a rubber ram, onthe other hand, the corrugation is drawn uniformly and simultaneously all round, and, in this case, the materialis able to flow, or the tube to decrease in lengthsimultaneously.

The process of manufacturing the flexible tubes according to the present invention consists, therefore,'in that the so-called'cres ts of the corrugations are first roughed out with a ram of yielding matter, by pressure in the outward direction, leaving, between the several corrugations, straight or plain cylindrical portions which then serve'for further working stages in the production of the troughs of the corrugations, these latter being formed by rollin inwards according to known processes. flowever, after about half of the designed corrugation has been forced outwards, there remains only about theother moiety to be rolled inwards, and therefore the stressing is not only far slighter,

1 but also fewer workingstages are suflicient.

' In order that the shape of the corrugations and also the distance between them, may be rendered exactly uniform in the outward pressing by means of the ram, itis preferable to emp oy a two-part external matrix provided with at least two profiles, one for shapingthe new corrugation, and'the other for the insertion of the corrugation already formed to ensure that the new corrugation will be accurately spaced in the same way as the preceding and succeeding corrugations.

The new process therefore enables flexible tubes tobemanufactured, not only with a deeper corrugations and increased elasticity,

together with more uniform wall thickness and of increased strength, but also in a far more rational manner, inasmuch as the outward pressing by meansof the yieldable ram I is able to replace severalfrolling stages with {out impairing the ductility of the material and without requiring nealmg of the material.

any intermediate anamples of the corrugations obtainable by means of the device;

Figs. 5 and 6 show diagrammatically how the corrugations can then be further treated in known manner, or how the flexible tubes can be further treated by rolling;

Fig. 7 is a detail view in perspective of the matrix showing only the upper one of the grooves;

Fig. 8 is a longitudinal section of the ram device showing how the crest of the first corrugation is made; and

Fig. 9 is a similar feature showing the corrugation made at a previous step inserted within the lower or spacing groove of the matrix so as to accurately determine the spacing of the next corrugation which is about to be made. i

Reference 1 denotes a plain 'tube'intended to serve for the production of a corrugated tube and composed of suitable ductile material, such as copper, brass, tombac, iron,

German silver or the like, whilst-2 denotes a two-part external matrixserving to shape and to take up-the pressure of the upper ram 1- against the' rubber ram. A guide stem 6 on I the upper metal-ram 71 extends throughthe rubber member 3 into the lower ram 5, in

which it slides so as to center the ram. It will be evident that the corrugations may alsobe formed, for example by a pressure fluidram, in place of the rubber ram.

7 and 7a (Figs. 5 and 6) are external rolls, with corresponding inner rolls 8 and8a, such as can be employed for finishing the flexible tubes.

I claim:

1. A process of manufacturing highly elas-' tic corrugatedtubes from plain metal tubes with thin walls, consisting in pressing out the crests of the corrugations leaving straight "cylindrical tube portions therebetween and thereafter forcing in the cylindrical tube portions between said crests to form the troughs of the corrugations. p p

2. A process of manufacturing-highly elastic corrugated tubes from plain metal'tubes with thin walls, consisting in subjecting the inside of the tube to outwardly directed pressure simultaneously-exerted along the entire circumference thereof so as to press out the crests of the corrugations, and thereafter rolling in the tube portions between said crests to form the troughs of the corrugations.

3. A process of manufacturing highly elastic corrugated tubes from plain metal tubes with thin walls, consisting in first pressing out the crests of the corrugations, leaving straight cylindrical tube portions therebetween, then forcing in the cylindrical tube portions between said crests to an approximately equal extent to form the troughs of the corrugations, and then subjecting the tubes to successive rollings with progressively narrower profile rolls to narrow and deepen the corrugations.

4. A process of manufacturing highly elastic corrugated tubes from plain metal tubes with thin walls, consisting in first subjecting the inside of the tube to outwardly directed pressure simultaneously exerted along the entire circumference thereof so as to press out the crests of the corrugations leaving straight cylindrical tube portions therebetween, then rolling in the cylindrical tube portions be tween said crests to form the troughs of the corrugations, and then subjecting the tubes to successive rollings with progressively narrower rolls to close up and deepen the corrugations.

5. As a new article of manufacture for use in pressing out the crests of corrugations to be formed in plain tubes, a divided ring matrix having at least two internal grooves ofthe' same shape as said crests, one of said grooves serving to form the corrugations and the other to accommodate the finished crests one after the other as the tube is fed stepwise through the matrix.

8. Apparatus for use in corrugating plain thin-walled metal tubes, comprising a twopart ring matrix having two internal annular grooves corresponding to the required shape of the corrugations, and a ram of flexible matter in the matrix for successively forcing portions of the wall of a tube fed stepwise over the ram and through the matrix into one of said grooves, the other of said grooves accommodating the finished corrugations one after another as the tube is advanced.

7. Apparatus for use in corrugating plain thin-walled metal tubes, comprising a twopart ring matrix having two internal annular grooves corresponding to the required shape of the corrugations, and a rubber ram in the matrix for successively forcing portions of the wall of a tube fed stepwise over the ram and through the matrix into one of said grooves, the other of said grooves accommodating the finished corrugations one after another as the tube is advanced.

8. Apparatus for use in corrugating plain thin-walled metal tubes, comprising a twopart ring matrix having two internal annular grooves corresponding to the required shape of the corrugations, and a yieldable ram device in the matrix for successively forcing portions of the wall of a tube fed stepwise over the ram and through the matrix into one of said grooves, the other of said grooves ac- 

